A. Hi wagar. There are more economical reagents to neutralize HCl, including lime or magnesium hydroxide; both are also safer than caustic, but each has limitations which must be worked around.

There are also ways to extend the life of the HCl bath, including better inhibitors (so less iron is consumed), and "acid extenders" (which precipitate the iron so the bath does not need to be dumped).

Q. Thank you for the quick response. We are using pickling inhibitor from Rodine. Do I continue to need inhibitor if I go for acid life extenders?

waqar haiderchemical synergies - karachi, pakistan

March 2017

A. Hi Wagar. Sorry, although I would expect that the Rodine continues to provide useful inhibition, so acid isn't wasted on raw steel, I don't really know.

In as much as both the Rodine and the acid life extender are secret proprietaries, it may be hard for anyone but the supplier to offer answers about their compatibility and symbiotic effects. I'd suggest that you ask the manufacturer of the acid extender. Good luck.

A. There are several acid purification technology that can reduce the amount of caustic needed by 75-90%. You may want to investigate diffusion dialysis, acid retardation, and evaporation as a solution to this problem.

Lyle KirmanConsultant - Cleveland Heights

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